1. Field of the Invention
The present invention relates generally to general purpose and industrial power transmission devices and, in particular, to a novel housing construction for gearboxes and gearmotors that allows a wide variety of mounting and torque support configurations.
2. Description of the Related Art
The vast majority of machinery utilizes rotational mechanical energy as a power input to perform a given function. This rotational mechanical energy is generated by a prime mover, such as an electric motor, hydraulic motor, gas engine, or the like, and in most cases is further "conditioned" to the required torque and speed level by using a geared reducer arrangement. The input torque and speed generating device (i.e., the driving device or drive) needs to be adequately supported by the structure or by the foundation of the machinery (i.e., the driven device) to generate the reaction torque necessary for the torque equilibrium.
The housing construction of the drive has to be designed and shaped appropriately to allow an easy attachment to the driven machinery, to secure the alignment of the drive and driven shaft, and to support the drive weight, thereby giving support to generate the required reaction torque. The most common mounting arrangements are mounting feet, flanges, brackets and torque arms. Torque arms are widely used with drive units having hollow bore output shafts where the solid shaft of the driven machinery is inserted into the bore of the driving unit. This type of drive arrangement (also called "shaft mount" gearboxes or gearmotors) secures inherently the alignment of the driven and drive shafts. The driven shaft also supports the weight of the drive. An appropriate torque arm arrangement is required to generate a reaction torque.
Currently, there are two basic types of torque support designs in use for parallel offset hollow shaft gearboxes and gearmotors. The first type is a tie rod type torque arm, which is attached to the gearbox at the one end and to the frame or foundation of the driven device at the other end, as shown in FIG. 1. The other type features an integrated torque arm plate with the housing, which is then connected to the driven machinery by a support bracket, arm, pin or plate, as shown in FIG. 2.
The first type, as shown in FIG. 1, is mainly used in gearboxes having a two piece housing construction. The torque arm (tie rod) is attached to the housing with bolts which hold the two gearbox halves together. The disadvantage of this arrangement is that substantial mounting space is required for the tie rods. Furthermore, it is necessary to use two tie rods with an opposite orientation to allow a torque transmittal in both directions. A long tie rod type torque arm arrangement can be desirable in some applications where the driven machinery has no sufficiently rigid structural part close to the gearbox, or where the accessible foundation is far from the drive.
The second type, as shown in FIG. 2, is more space saving because the integrated torque arm can be easily connected with a short support arm or rib of the driven machinery. This design allows a compact drive attachment and torque support arrangement which can support the torque in both rotational directions. However, due to the shape, orientation and position of the integrated torque arm, a tie rod support is not possible. Accordingly, there is a need for more versatile and compact housing constructions for gearboxes and gearmotors to allow for a wider variety of mounting and torque support configurations.